An exhibitor presents bird houses made from recycled plastic during the San Francisco International Gift Fair in San francisco, the United States, July 28, 2013. The four-day fair kicked off on Saturday. (Xinhua/Liu Yilin)

An exhibitor presents exhibits during the San Francisco International Gift Fair in San francisco, the United States, July 28, 2013. The four-day fair kicked off on Saturday. (Xinhua/Liu Yilin)